Process of refining and treating petroleum hydrocarbons



June 30, 1942. w, T. HANCOCK 2,288,131 PROCESS oF REFINING AND TREATING PETROLEUM HYDRocARBoNs Filed Jan. 10, 1940 Patented June 30, 1942 OFFICE PROCESS OF REFINING AND TREATING PETROLEUM HYDROGARBONS William T. Hancock, Long Beach, Calif.

Application `lanuary 10, 1940, Serial No. 313,223

7 Claims.

This invention has to do with processes for the cracking and refining of petroleum hydrocarbons to produce gasoline, and has for its general object to provide an improved system that is Darticularly adaptable for the cracking of relatively low boiling cracking stocks to produce high yields of gasoline having abnormally high octane rating.

The invention may be further characterized as incorporating in a cracking system, a method of subjecting the cracked hydrocarbons to polymerization by contacting them with adsorptive material, and further, if desired, of subjecting relatively heavy fractions of the polymerized hydrocarbons to recracking, all with the object of converting a given cracking stock into maximum potential gasoline forming constituents, and reforming these constituents by polymerization into condensable gasoline fractions. By reason of the adaptability of the system to initial dissociation of the cracking stock into high percentages of potential aromatic and other non-detonating type hydrocarbons, and then the conversion by polymerization or catalytic action of the cracked products into such hydrocarbons, it is made possible to produce an exceptionally high quality gasoline.

Preferably the system is operated using, as stated, a relatively low boiling charging stock which is subjected to vaporization and cracking and the vapors introduced to a polymerizing zone wherein they are intimately contacted with a suitable catalytic or adsorptive material. Particularly where it is desired to introduce all the cracked hydrocarbon directly from the cracking zone into the polymerizing chamber, provision is made for maintaining liquid and Vapor fractions of the hydrocarbons in intimate contact within the adsorptive material so as to increase its catalytic and polymerizing effectiveness, and to accomplish by washing action, the removal from the material of contaminating bodies such as carbon or heavy hydrocarbons and polymers.

Unvaporized or condensed relatively heavy fractions of the hydrocarbons subjected to polymerization, are recirculated for cracking in a second cracking zone, the cracked hydrocarbons from which are polymerized by passing them through the adsorptive material in the polymerizing zone receiving hydrocarbons from the first mentioned cracking zone, or delivered to a second similar polymerizing zone. Condensate or unvaporized oil thus recirculated for cracking may be taken from one or both polymerizing both cracking zones may be subjected to treatment to produce the product gasoline by any suitable method, as by subjecting the vapors to fractionation and then final condensation.

The operation of the invention and the various features and objects mentioned in the foregoing, will be further explained and understood to better advantage from the following description of a typical system embodying the invention, illustrated diagrammatically and in flow sheet form in the accompanying drawing.

The preferred charging stock may comprise relatively low octane gasoline, kerosene distillate and in general hydrocarbons that are sufficiently low boiling not to produce excessive carbon or residue contamination of clay in the conversion zone. The charging stock is delivered from line I0 to the cracking still II wherein the hydrocarbons may be subjected to cracking in either liquid or vapor phase, or mixed liquid and vapor phase, at a temperature that typically may range from 800 to 1200 F. under Vsuitable pressure of for example 50 to 400 lbs. per sq. in. Leaving the cracking still, the cracked hydrocarbon stream is discharged through line I2 into a shell or chamber I3 containing a suitable comminuted siliceous material, preferably adsorptive clay such as fullers earth, Murock or Death Valley clays, and the like. As will be understood, the

clay may also contain or have been pre-treatedV with any or a mixture of known substances of a reactive or catalytic nature, adapted in the case of the former to react with and thereby accomplish the removal of impurities such as acid or sulfur constituents of the hydrocarbons, and in the case of the catalysts, to catalyze the cracking reaction, or to induce more complete polymerization. Various metals, metallic oxides and metallic salts are commonly known as suitable reactive or catalytic agents. Entering chamber I3, the hydrocarbons are intimately contacted with the adsorptive material I4, the vapors rising upwardly through the material to the outlet line I5, and any unvaporized fractions flowing downward to the bottom of the chamber where they are taken on through line I6.

Where the cracked hydrocarbons are discharged from still Il directly into a clay column, as in the typical system illustrated, it is important from both the standpoints of producing maximum catalytic or polymerizing action of the clay, and of maintaining the latter as free as possible from contamination by carbon or heavy residual .bodies carried in the cracked hyzones. The combined `polymerized vapors from drocarbon stream, that a mixture of liquid and vapor fractions be maintained in intimate contact and agitated washing action within the clay. For this purpose I may deliver to the upper interior of the clay column a suitable light hydrocarbon reflux, or produce the necessary reflux by partial condensation of the cracked vapors, so that the vapors rising Within the clay are contacted with a down-ilowing stream of reiiux, the two phases being intimately commingled and maintained in such a state of Washing agitation as to eiectively remove solid or heavy bodies from the clay to the draw ofi line I3.

Reflux to be introduced to the clay column may be taken, for example, from the supply line I and discharged directly through lines Il', I8 and I9 into the top of chamber |3, or the oil may be pre-heated in coil 29 to a suitable temperature that may approach the outlet vapor temperature of the clay column, before being introduced thereto. Optionally, a suitable reilux may be derived from a later stage in the system, as from the base of fractionating column 2| through line 22. Instead of introducing reiiux from an extraneous source, the reilux may be produced solely by partial condensation of the vapors, within the column. For example, a suitable cooling fluid may be circulated through a coil 23, the turns of which are contained within the body of adsorptive material I4 so that the vapors undergo condensation and liquid condensate and reflux are formed within the body of material itself. As will be understood, suicient condensate is produced to maintain a substantial quantity of liquid hydrocarbons in intimate contact with the vapors and in agitated washing flow within the adsorptive material. The oil drawn from the base of column I3 through line I6, and including hydrocarbons heavier than gasoline, and perhaps also heavier fractions within the gasoline range, depending upon the charging stock and particular temperature and pressure conditions, is taken through line 24 to a cracking still 25.

In still 25 the oil is subjected to cracking at temperatures and pressures that may be within the ranges stated with reference to cracking still I, although generally it is preferred to crack the oil in still 25 at somewhat higher temperature and pressure, say within 50 to 100 F. higher Vtemperature and up to 100 lbs. per sq. in. higher pressure, in view of the higher boiling range of the charging stock in still 25 where a lower boiling charging stock is being cracked in still I I. The cracked hydrocarbon stream is discharged through line 26 into a separating chamber or reaction zone 2l, from the base of which carbon and unvaporized residue are withdrawn from the system through line 28. The cracked vapors flowing from chamber 2'! through line 29 may be discharged through line 30 to be combined with the cracked hydrocarbon stream from the still I I and thereby recirculated through chamber I3, or a part of all of the vapors may be taken from line 29 through line 3| and discharged at 32 into a second polymerizing chamber 33 charged with siliceous or catalytic material 34 of the same character as that contained in chamber I3. The polymerized vapors leaving chamber I3 through line I5 may also be passed into chamber 33 through line 34a, or all or a portion of the vapors may be discharged through line 35 directly to the dephlegmator or fractionating column 2|.

The vapors introduced through line 32 to column 33 may be permitted to flow throughout adsorptive material 34 therein without introducing' reilux thereto or without producing abnormal condensation of the vapors, or a suitable reux may be introduced through line 36 or the vapors partially condensed by coil 31, all as previously described in connection with the operation of clay column I3. As an alternative method of maintaining mixed liquid and vapor contact within chamber 33, valve 31a in the outlet line 38 may be operated by a liquid level control, diagrammatically indicated at 39, which maintains Within the bottom of the chamber a minimum oil level L, below which the vapors are introduced from line 32 into a body of the oil. In this manner the oil is being continuously displaced upwardly Within the clay body by the vapor iiow, producing thorough commingling of the oil and vapor and their intimate contact with the clay. Condensate removed from chamber 33 through line 38, and carrying polymerized and sulfur containing hydrocarbons as in the case of the oil stream in line I6, may be recirculated through line 39 to the cracking still 25, or discharged to storage through line 40. Vapors leaving chamber 33 through line 4| flow through line 35 to fractionating column 2|, from the base of which heavier than gasoline fractions are withdrawn through line 42, and returned through line 42a to still 25, or taken to storage through line 42D. Leaving column 2|, the vapors pass through line 43 to a final condenser 44 from Which the condensate goes to receiver 45 and fixed and uncondensible vapors to the valved discharge line 46. As will be understood, fractionating column 2| and condenser 44 are merely illustrative of any suitable system for fractionating or further treating the vapors beyond the second clay column 33 to produce gasoline as a final product. The various vapor lines in the system are shown to contain valves which may be set to maintain proper operating pressures within the system, including the back pressures on the cracking stills, polymerizing chambers, fractionating column and iinal condenser. While generally it is preferred to control the pressure on the system by a valve or valves beyond the fractionating column, it will be apparent that the valves in the vapor lines may be regulated to maintain any desired diierential pressures on the hydrocarbons within the cracking stills, polymerizing chambers and fractionating column.

While the invention contemplates using preferably and more generally al charging stock for cracking still consisting of a relatively low boiling oil, as previously described, it is possible to adapt the system to operation onv heavier charging stocks by providing for the removal from the cracked hydrocarbon stream of carbon and heavy bodies that might otherwise produce excessive contamination of the adsorptive material in column I3. Where such heavier charging stock is employed, the cracked vapors leaving still YII may be discharged through line 48 into a separating or reaction chamber 49 from which the vapors flow through line 50 to the clay column I3, and the unvaporized residuum is removed from the system through line 5|.

From the foregoing description of the system,v

it will be seen that after initial cracking of the charging stock and initial polymerization ofthe vapors in chamber I3, relatively heavy fractions of the cracked hydrocarbons, as well as the polymerized bodies, are subjected to recracking and again subjected to polymerization in oneV or bothof the clay columns, all in a manner such that an abnormally high percentage of potential aromatic or other high octane value hydrocarbons is formed and converted Within the system to gasoline fractions. As a result, I obtain a final gasoline distillate that is abnormally high in aromatic and non-detonating compounds, and which possesses an exceptionally high octane rating.

I claim:

1. The method of refining petroleum hydrocarbons that includes subjecting the hydrocarbons to cracking in a cracking zone, introducing cracked hydrocarbon vapors from said zone into a polymerizing zone containing a body of adsorptive material being constantly Washed by condensed fractions of the vapors, passing the vapors through and in intimate contact With said material and condensate, removing polymercontaining unvaporized oil and condensate from said polymerizing zone, subjecting the removed oil and condensate to cracking in a second cracking and essentially non-hydrogenating zone separately from and independently of the vapors passing from the first mentioned cracking zone,

`subjecting cracked vapors from said second cracking zone to polymerization by contacting them with adsorptive material together With the irst mentioned vapors, and treating the polymerized vapors from the hydrocarbons cracked in said cracking zones to produce gasoline.

2. The method of refining petroleum hydrocarbons that includes subjecting the hydrocarbons to cracking in a cracking zone, introducing cracked hydrocarbon vapors from said zone into a polymerizing zone containing a body of adsorptive material being constantly washed by condensed fractions of the vapors, passing the vapors through and in intimate Contact With said material and condensate, removing polymer-- containing unvaporized oil and condensate from said polymerizing zone, subjecting the removed oil and condensate to cracking in a second cracking and essentially non-hydrogenating zone separately from and independently of the vapors passing from the iirst mentioned cracking zone, subjecting cracked vapors from said second cracking zone to polymerization by contacting them with adsorptive material together with the first mentioned vapors in said polymerizing zone, and treating the polymerized vapors from the hydrocarbons cracked in said cracking zones to produce gasoline.

3. The method of refining petroleum hydrocarbons that includes subjecting the hydrocarbons to cracking in a cracking zone, introducing cracked hydrocarbon vapors from said zone into a polymerizing zone containing a body of adsorptive material being constantly Washed by condensed fractions of the vapors, passing the vapors through and in intimate contact with said material and condensate, removing polymercontaining unvaporized oil and condensate from said polymerizing zone, subjecting the removed oil and condensate to cracking and vaporization in a second cracking and essentially non-hydrogenating zone separately from and independently of the vapors passing from the first mentioned cracking zone, separating unvaporized residuum from the resulting vapors and subjecting the last mentioned vapors to polymerization by contacting them with adsorptive material together with the first mentioned vapors, and treating the polymerized vapors from the hydrocarbons cracked in said cracking zones to produce gasoline.

4. The method of refining petroleum hydrocarbons that includes subjecting the hydrocarboris to cracking in a cracking zone, introducing cracked hydrocarbon vapors from said zone into a polymerizing zone containing a body of adsorptive material being constantly Washed bv condensed fractions of the vapors, passing the vapors through and in intimate contact with saidmaterial and condensate, removing polymercontaining unvaporized oil and condensate from said polymerizing zone, subjecting the removed oil and condensate to cracking and vaporization in a second cracking and essentially non-hydrogenating zone separately from and independently of the vapors passing from the first mentioned cracking zone, separating unvaporized residuum from the resulting vapors and subjecting the last mentioned vapors to polymerization by contacting them with adsorptive material together with the first mentioned vapors in said polymerizing zone, and treating the polymerized vapors from the hydrocarbons cracked in said cracking zones to produce gasoline.

5. The method of refining petroleum hydrocarbons that includes subjecting the hydrocarbons to cracking in a cracking zone, introducing cracked hydrocarbon vapors from said zone intc a polymerizing zone containing a body of adsorptive material being constantly Washed by condensed fractions of the vapors, passing the vapors through and in intimate contact with said material and condensate, removing polymercontaining unvaporized oil and condensate from said polymerizing zone, subjecting the removed oil and condensate to cracking and vaporization in a second cracking and essentially non-hydrogenating zone separately from and at a ternperature higher than the temperature of the vapors leaving the first mentioned cracking zone, separating unvaporized residuum from the resulting vapors and subjecting the last mentioned vapors to polymerization by contacting them with adsorptive material together with the first mentioned vapors, and treating the polymerized vapors from the hydrocarbons cracked in said cracking zones to produce gasoline.

6. The method of rening petroleum hydrocarbons that includes subjecting the hydrocarbons to cracking in a cracking zone, passing cracked hydrocarbon vapors from said zone successively through two polymerizing zones each containing a large, vertically extending body of adsorptive material, maintaining the vapors in intimate contact with said material in the presence of condensed fractions of the vapors, removing polymer-containing condensate from the polymerizing zone first entered by the vapors, subjecting the removed condensate to cracking in a second cracking and essentially non-hydrogenating zone separately from and independently of the vapors passing from the first mentioned cracking zone, separating unvaporized residuum from the resulting vapors and subjecting the last mentioned vapors to polymerization ,together ence of condensed fractions of the vapors, removing polymer-containing condensate from both said polymerizing zones, subjecting the removed condensate to cracking in a second cracking and essentially non-hydrogenatng zone 5 separately from and independently of the vapors passing from the first mentioned cracking zone` separating unvaporized residuum from the re- WILLIAM T. HANCOCK. 

